Lexical Definition

‎יַהֲלֹם‎ yahălôm (yah-hal-ome') jasper ^H:N-M
from ‎הָלַם‎ (in the sense of hardness)

diamond.

• a precious stone, probably onyx

1) a precious stone (known for its hardness)
1a) perhaps the jasper, onyx, or diamond

See Greek: ἴασπις · σμάραγδος

Brown-Driver-Briggs

‎יַהֲלֹם‎ noun [masculine] a precious stone, jasper ? (so ᵐ5 ᵑ9), or onyx? (compare Di Exod 28:18) (apparently from √ ‎הלם‎; owing to its hardness, as able to smite, hammer?) — mentioned in lists of precious stones Exod 28:18; Exod 39:11; Ezek 28:13.

Brown-Driver-Briggs References